Multi-dimensional force sensing for scanning probe microscopy using carbon nanotube tips and carbon nanotube oscillators

Abstract

A system and method of multi-dimensional force sensing for scanning probe microscopy is provided.

1. A scanning probe microscopy (SPM) tool, comprising:
 an oscillator portion; 
 a nanotube tip portion extending from said oscillator portion; 
 said oscillator portion comprising a first resonant mode defined by at least one of, a selected shape of said oscillator portion, a selected dimensions ratio of said oscillator portion, a selected material composition of said oscillator portion, and a selected location of said nanotube tip portion on said oscillator portion, such that when said oscillator portion is oscillated at a first natural resonant frequency of said oscillator portion while said nanotube tip apex is at a surface of a sample, said SPM tool is sensitive to a first component of a resultant surface force interaction between said nanotube tip portion and said sample surface in a first direction, wherein said first force interaction component causes detectable alterations in said first natural resonant frequency; and 
 said oscillator portion comprising a second resonant mode defined by at least one of, said selected shape of said oscillator portion, said selected dimensions ratio of said oscillator portion, said selected material composition of said oscillator portion, and said selected location of said nanotube tip portion on said oscillator portion, such that when said oscillator portion is oscillated at a second natural resonant frequency of said oscillator portion while said tip apex is at said sample surface, said SPM tool is sensitive to a second component of said resultant surface force interaction in a second direction, wherein said second force interaction component causes detectable alterations in said second natural resonant frequency, and wherein said second direction is different from said first direction; 
 an excitation system adapted to vibrate said oscillator portion at said resonant modes; 
 a sensing system adapted to detect and measure movements of said oscillator portion; 
 a mechanical actuation system adapted to position said nanotube tip and said sample surface relative to each other; and 
 a feedback control system adapted to control said actuation system based on outputs of said sensing system. 
 
     
     
       2. A force sensor for use in scanning probe microscopy, comprising:
 an oscillator; 
 a nanotube extending from said oscillator; and 
 wherein said oscillator and said nanotube are adapted to sense surface force interactions between said nanotube and a sample surface in at least one direction utilizing at least one resonant frequency of said nanotube. 
 
     
     
       3. A scanning probe microscopy tool with a force sensor in accordance with  claim 2 , having:
 an actuator for positioning said nanotube and said sample relative to each other; 
 a vibration device for exciting said nanotube at said resonant frequency; 
 a sensing system for providing an output based on said surface force interactions in said direction; and 
 a feedback control system for scanning said actuator based on said output. 
 
     
     
       4. A scanning probe microscopy tool in accordance with  claim 3 , wherein said surface force interactions are caused by at least one force selected from the group consisting of: electrostatic force, magnetic force, atomic force, electromagnetic force, chemical force, mechanical force, and biological force. 
     
     
       5. A scanning probe microscopy tool in accordance with  claim 3 , wherein said surface force interactions are from any combination of at least two forces selected from the group consisting of: electrostatic force, magnetic force, atomic force, electromagnetic force, chemical force, mechanical force, and biological force. 
     
     
       6. A force sensor for use in scanning probe microscopy, comprising:
 an oscillator; 
 a nanotube tip extending from said oscillator; and 
 wherein said oscillator is adapted to sense surface force interactions between said nanotube tip and a sample surface in a first direction with a first resonant frequency, and simultaneously in a second direction with a second resonant frequency. 
 
     
     
       7. A force sensor in accordance with  claim 6 , wherein said oscillator is simultaneously sensitive to surface force interactions between said tip and said sample surface in a third direction with a third resonant frequency. 
     
     
       8. A force sensor in accordance with  claim 6 , wherein said first direction and said second direction are orthogonal to each other. 
     
     
       9. A scanning probe microscopy tool with a force sensor in accordance with  claim 6 , having:
 an actuator for positioning said nanotube tip and said sample relative to each other; 
 a vibration device for exciting said oscillator at said first and said second resonant frequencies simultaneously; 
 a sensing system for providing a first output based on said surface force interactions in said first direction and for providing a second output based on said surface force interactions in said second direction; and 
 a feedback control system for scanning said actuator based on said first and second outputs. 
 
     
     
       10. A force sensor for use in scanning probe microscopy, comprising:
 a support structure portion; 
 at least one nanotube oscillator grown directly onto and extending from said support structure portion; and 
 wherein said at least one nanotube oscillator is adapted to sense force interactions between said at least one nanotube oscillator and a sample in at least one direction utilizing at least one resonant frequency of said at least one nanotube oscillator. 
 
     
     
       11. A scanning probe microscopy system with a force sensor in accordance with  claim 10 , having:
 an actuator system for positioning said nanotube oscillator and said sample relative to each other; 
 an excitation system for exciting said nanotube oscillator at said resonant frequency; 
 a sensing system for providing an output based on said force interactions in said direction; and 
 a feedback control system for scanning said actuator based on said output. 
 
     
     
       12. A scanning probe microscopy system in accordance with  claim 11 , wherein said force interactions are caused by at least one force selected from the group consisting of: electrostatic force, magnetic force, atomic force, electromagnetic force, chemical force, mechanical force, and biological force. 
     
     
       13. A scanning probe microscopy system in accordance with  claim 11 , wherein said force interactions are from any combination of at least two forces selected from the group consisting of: electrostatic force, magnetic force, atomic force, electromagnetic force, chemical force, mechanical force, and biological force. 
     
     
       14. A scanning probe microscopy system in accordance with  claim 11 ,
 wherein said nanotube has a magnetic particle at a distal end of said nanotube, and 
 wherein said excitation system comprises a device adapted to provide a magnetic coupling to said magnetic particle. 
 
     
     
       15. A force sensor for use in scanning probe microscopy, comprising:
 a support structure portion, 
 at least two nanotubes grown directly onto and extending from said support structure portion in different directions; and 
 wherein each said nanotube has controllable orientation with respect to a sample surface. 
 
     
     
       16. A force sensor in accordance with  claim 15 , wherein each of said nanotubes are perpendicular to each other. 
     
     
       17. A force sensor in accordance with  claim 15 , wherein five of said nanotubes extend from said support structure portion in said different directions, and wherein each of said five nanotubes is substantially perpendicular to its adjacent nanotubes of said five nanotubes. 
     
     
       18. A force sensor in accordance with  claim 15 , wherein at least one of said controllable orientations is substantially perpendicular to at least one said sample surface. 
     
     
       19. A force sensor for use in scanning probe microscopy, comprising:
 a support structure portion comprising a tip, 
 a single nanotube grown directly onto and extending from said support structure portion; and 
 wherein said nanotube is grown substantially perpendicular to a primary axis of said tip. 
 
     
     
       20. A force sensor in accordance with  claim 19 , wherein said tip support structure portion is a silicon tip with a high-aspect-ratio generally conical shape. 
     
     
       21. A force sensor for use in scanning probe microscopy, comprising:
 a support structure portion, 
 a single nanotube grown directly onto and extending from said support structure portion; and 
 wherein said support structure portion is a column. 
 
     
     
       22. A force sensor for use in scanning probe microscopy, comprising:
 a support structure portion, 
 a single nanotube grown directly onto and extending from said support structure portion; and 
 wherein said nanotube has a magnetic particle at the distal end of said nanotube. 
 
     
     
       23. A device, comprising:
 a support structure portion; 
 a nanotube grown directly onto and extending from said support structure portion; and 
 a magnetic particle grown directly near the free end of said nanotube. 
 
     
     
       24. A force sensor for use in scanning probe microscopy, comprising:
 an oscillator; 
 a nanotube extending from said oscillator; and 
 wherein said oscillator and said nanotube are adapted to sense surface force interactions between said nanotube and a sample surface in at least one direction utilizing at least one resonant frequency of said nanotube and at least one resonant frequency of said oscillator. 
 
     
     
       25. A force sensor for use in scanning probe microscopy, comprising:
 an oscillator; 
 a nanotube grown directly onto and extending from said oscillator; and 
 wherein said oscillator and said nanotube are adapted to sense surface force interactions between said nanotube and a sample surface in at least one direction utilizing at least one resonant frequency of said nanotube and at least one resonant frequency of said oscillator. 
 
     
     
       26. A force sensor for use in scanning probe microscopy, comprising:
 a support structure portion; 
 a nanotube oscillator grown directly onto and extending from said support structure portion; and 
 wherein said nanotube oscillator is excited and sensed so as to detect force interactions between said nanotube and a sample in at least one direction. 
 
     
     
       27. A force sensor for use in scanning probe microscopy, comprising:
 a support structure portion, 
 a single nanotube grown directly onto and extending from said support structure portion; and 
 wherein said single nanotube is grown substantially perpendicular to a vertical surface.